Keyboard



FIG. 1 is an isometric view of a keyboard embodying our new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a side elevational view thereof; and

FIG. 5 is a rear elevational view thereof. 

The ornamental design for a keyboard, substantially as shown and described. 